JCLOUDS-166, JCLOUDS-167 - Removing async from vcloud and Terremark APIs/providers
Cleanup of Client->Api getters for vcloud
Add trailing slash to Atmos listDirectories

This is more consistent with examples in the Atmos programmer's guide
and allows this operation to succeed when used with ViPR.
Reduce testPutFileParallel input size to ~160 KB

Previously this test uploaded ~10 MB in 30 seconds which failed on
slower connections, causing spurious test failures.  The larger input
size provides no benefit.
Run some filesystem integration tests

Previously no integration tests ran, now we see:

Tests run: 43, Failures: 0, Errors: 0, Skipped: 8
Enable some Xlint warnings

Also address a handful of warnings.
Reduce testFileGetParallel input size to ~160 KB

Previously this test downloaded 45 MB in 30 seconds which failed on
slower connections, causing spurious test failures.  The larger input
size provides no benefit.
Upgrade to Guava 15.0-rc1

Release notes:

https://code.google.com/p/guava-libraries/wiki/Release15
[trivial] Simplify use of Optional.or

Also correct checkArgument call.
Explain expected result in filesystem test
Upgrade to Guava 15.0

Release notes:

https://code.google.com/p/guava-libraries/wiki/Release15
Revert "Disable timed temporary signed URLs for AWS-S3"

This reverts commit bc0abbaa073a9178f3aeb0d1541ea5fc50dded35 and
re-enables temp-signed URLs for S3.

Closes JCLOUDS-200
Delete containers after integration tests

Also return newly allocated containers to the pool.
[trivial] Remove unused variables
Add Atmos-specific MD5 checksum header

Tested that Atmos Online and Synaptic Atmos both enforce this.